Have you ever meticulously scraped off the blackened edges of your toast? Or perhaps wondered if that slightly charred pizza crust is doing you any harm? Recent research is prompting us to reconsider the potential risks associated with consuming burnt food. Let’s delve into the science behind this common culinary occurrence and explore what you should know to protect your health.
In 2002, a pivotal discovery by scientists at the University of Stockholm shed light on a concerning substance called acrylamide. This chemical compound forms when certain foods, particularly those rich in carbohydrates like potatoes, bread, biscuits, cereals, and even coffee, are subjected to high heat exceeding 120°C (248°F). The Maillard reaction, a chemical process between sugars and amino acids (specifically asparagine), is responsible for the desirable browning and characteristic flavors we associate with cooked food. However, it also inadvertently leads to the creation of acrylamide.
While the Maillard reaction is essential for flavorful cooking, it can unfortunately produce acrylamide.
Studies have demonstrated that acrylamide is carcinogenic in animals, but only at significantly higher doses than typically found in human food. The European Food Safety Authority suggests that acrylamide could potentially increase the risk of cancer in humans, especially in children. However, research on human subjects has yet to provide definitive conclusions.
Fatima Saleh, associate professor of medical laboratory sciences at Beirut Arab University in Lebanon, notes, “After almost 30 years of its classification as a ‘probable human carcinogen’, there is still inconsistent evidence of its definite carcinogenicity in humans. However, if we continue to do further studies on humans, we might have adequate data to change acrylamide’s classification to a human carcinogen.”
Beyond its potential carcinogenic effects, acrylamide is known to be neurotoxic to humans. This means it can negatively impact the nervous system. The precise mechanisms remain under investigation, but theories suggest that acrylamide may target structural proteins within nerve cells or inhibit anti-inflammatory processes that safeguard nerve cells from damage. Furthermore, the toxic effects of acrylamide are believed to be cumulative, meaning that even small amounts consumed over extended periods could pose long-term risks to organ health.
Federica Laguzzi, assistant professor of cardiovascular and nutritional epidemiology at the Institute of Environmental Medicine at Karolinska Institutet in Sweden, emphasizes the importance of this cumulative effect, stating that prolonged exposure to dietary acrylamide might elevate the risk of neurodegenerative diseases like dementia and potentially contribute to neurodevelopmental disorders in children, based on animal studies.
Removing burnt parts of food could mitigate the potential long-term health risks associated with acrylamide.
Laguzzi also highlights a concerning link between higher acrylamide intake in pregnant individuals and adverse outcomes in newborns, including lower birth weight, head circumference, and length. “Acrylamide passes through all tissue, including the placenta, because it has a low molecular weight and is soluble in water,” she explains.
Leo Schouten, an associate professor of epidemiology at Maastricht University in the Netherlands, proposes that the potential cancer-causing effects of acrylamide might be linked to hormonal disruptions. His research team discovered a higher risk of endometrial and ovarian cancers in women with high acrylamide exposure, which led them to investigate hormonal mechanisms.
Soaking potatoes in water before cooking can significantly reduce acrylamide formation.
“Acrylamide may affect oestrogen or progesterone, which would explain the female cancers, but this hasn’t been proven,” says Schouten. Studies on rats have also shown connections between acrylamide consumption and cancer in hormone-sensitive tissues, further suggesting a potential hormonal pathway.
Given these concerns, the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives has advocated for more extensive long-term research to clarify the relationship between acrylamide and cancer. They also support efforts to minimize acrylamide levels in food production.
One of the key challenges in assessing the risk of acrylamide lies in accurately measuring human consumption. As Laguzzi points out, many studies rely on dietary questionnaires, which are prone to recall bias. While some researchers like Schouten believe they have developed methods for accurately measuring acrylamide intake, the scientific community remains divided. Measuring biomarkers in urine and blood offers an alternative approach, but so far, these measurements haven’t led to definitive conclusions.
Despite the uncertainties, there is growing evidence suggesting that acrylamide intake and deaths from cancer are linked. It’s also possible that our bodies possess protective mechanisms that help limit the risks associated with acrylamide.
The food industry is proactively addressing the issue. The EU is working on establishing maximum allowable levels for acrylamide in food, which could significantly impact the food supply chain. Nigel Halford’s research focuses on reducing asparagine levels in wheat, thus minimizing acrylamide formation in wheat-based products. He uses gene editing techniques like Crispr to achieve this.
Many producers are also striving to lower the acrylamide content of their products, particularly in baby food. This has led to notable reductions in acrylamide levels in certain foods.
Individuals can also take simple steps at home to minimize acrylamide formation during cooking. Soaking cut potatoes in hot water for 10 minutes before frying can reduce acrylamide formation by up to 90%.
While research is still ongoing, the scientific interest in the health risks associated with acrylamide is steadily increasing. As Laguzzi notes, further studies are needed to clarify the connection between acrylamide intake and cancer risk. In the meantime, it might be wise to stick with the habit of scraping the burnt bits off your toast.
Further research is crucial to understand the long-term health effects of consuming burnt food.
